Bad crossover?
fattmann
Posts: 58
I am having some deep technical issues with my TSi500s that I have had for a good while.
Signal chain: Laptop->Steinberg UR22MkII-> Yamaha 1065->TSi500.
Using a Dayton EMM-6 and REW for measurements
I setup REW to do some room measurements, and noticed a severe dip in my high frequencies. After some experimentation, I determined that the tweeter in my left tower was bad. I pulled it out, and it reads full short with continuity tester. I also pulled the right tower's tweeter and it reads a solid 4.0 Ohms.
While both tweeters were out, I decided to run additional sweeps in just the high frequencies to confirm the bad tweeter. These sweeps were done with the jumpers removed, and only the upper terminals connected. I noticed that there was an odd roll off, and realized the problem is deeper than my bad tweeter.
Two of the attached plots show a sweep from 10kHz-20kHz. There is a clear roll off for the right tower that shows the mids are still doing some lifting in the high freqs that isn't there on the left tower.
I also generated some pink noise and held my RadioShack SPL meter about arms length from each tower, there was about a 6dB reduction on the "better" right tower.
I connected the right tower to the left output of the Yamaha to confirm that it wasn't and AVR issue. Same results on both the REW sweep, and the SPL meter.
I'm not sure what else to try to confirm what the issue is, short of a complete teardown of the towers, removing all drivers and crossovers- which I have never done. It might be important to note that the tweeters on both towers were replaced about 5yrs ago. I had a moment of clutz and didn't power the system down before unplugging and a high frequency chirp fried both in one swoop.
Would these diagnostic results indicate a faulty crossover? Could a bad crossover have damaged a replaced tweeter? In my head I would think yes, if it failed in a way that low freqs were being sent to the tweeter. I don't have any experience with a failing crossover, so I'm not sure.
Any suggestions for more diagnostics I could run (white/pink noise SPL readings, sin wave SPL readings, frequency sweeps in REW, anything- I'm somewhat savvy), or any other suggestions in general would be greatly appreciated.
If it comes down to just the crossover being bad and all the drivers are good, I may take a stab at a custom crossover. I know there are a few threads out there on crossover upgrades for the Polk towers. I would have loved for it to just have been the bad tweeter, but my signs are pointing to a deeper issue.
Am I totally off track?
RIGHT TOWER HIGH FREQ
LEFT TOWER HIGH FREQ
RIGHT TOWER FULL SWEEP
LEFT TOWER FULL SWEET
OVERLAY
Signal chain: Laptop->Steinberg UR22MkII-> Yamaha 1065->TSi500.
Using a Dayton EMM-6 and REW for measurements
I setup REW to do some room measurements, and noticed a severe dip in my high frequencies. After some experimentation, I determined that the tweeter in my left tower was bad. I pulled it out, and it reads full short with continuity tester. I also pulled the right tower's tweeter and it reads a solid 4.0 Ohms.
While both tweeters were out, I decided to run additional sweeps in just the high frequencies to confirm the bad tweeter. These sweeps were done with the jumpers removed, and only the upper terminals connected. I noticed that there was an odd roll off, and realized the problem is deeper than my bad tweeter.
Two of the attached plots show a sweep from 10kHz-20kHz. There is a clear roll off for the right tower that shows the mids are still doing some lifting in the high freqs that isn't there on the left tower.
I also generated some pink noise and held my RadioShack SPL meter about arms length from each tower, there was about a 6dB reduction on the "better" right tower.
I connected the right tower to the left output of the Yamaha to confirm that it wasn't and AVR issue. Same results on both the REW sweep, and the SPL meter.
I'm not sure what else to try to confirm what the issue is, short of a complete teardown of the towers, removing all drivers and crossovers- which I have never done. It might be important to note that the tweeters on both towers were replaced about 5yrs ago. I had a moment of clutz and didn't power the system down before unplugging and a high frequency chirp fried both in one swoop.
Would these diagnostic results indicate a faulty crossover? Could a bad crossover have damaged a replaced tweeter? In my head I would think yes, if it failed in a way that low freqs were being sent to the tweeter. I don't have any experience with a failing crossover, so I'm not sure.
Any suggestions for more diagnostics I could run (white/pink noise SPL readings, sin wave SPL readings, frequency sweeps in REW, anything- I'm somewhat savvy), or any other suggestions in general would be greatly appreciated.
If it comes down to just the crossover being bad and all the drivers are good, I may take a stab at a custom crossover. I know there are a few threads out there on crossover upgrades for the Polk towers. I would have loved for it to just have been the bad tweeter, but my signs are pointing to a deeper issue.
Am I totally off track?
RIGHT TOWER HIGH FREQ
LEFT TOWER HIGH FREQ
RIGHT TOWER FULL SWEEP
LEFT TOWER FULL SWEET
OVERLAY
Components in The Rack:
Yamaha RX-V765 7.1 AVR
Sony TA-N511 (from 1065 to sub)
Xbox One
MA PD-915R Power Strip
Monster HTS-1650
Speakers:
L/R- Polk TSI-500 Cherry, 12awg in place of jumpers
C- Polk CS20 Cherry
SRs- Polk TSI-100 Cherry
Sub- Kicker S12L5, vented box
Display:
Sony VPH-1252Q
75" 16:9 DIY BO Cloth Screen
Not running:
Crown Straight Line Two
Crown Power Line Four
Pioneer PD-F908
Fender BXR Dual Bass 400
Pioneer BDP-51
Yamaha RX-V765 7.1 AVR
Sony TA-N511 (from 1065 to sub)
Xbox One
MA PD-915R Power Strip
Monster HTS-1650
Speakers:
L/R- Polk TSI-500 Cherry, 12awg in place of jumpers
C- Polk CS20 Cherry
SRs- Polk TSI-100 Cherry
Sub- Kicker S12L5, vented box
Display:
Sony VPH-1252Q
75" 16:9 DIY BO Cloth Screen
Not running:
Crown Straight Line Two
Crown Power Line Four
Pioneer PD-F908
Fender BXR Dual Bass 400
Pioneer BDP-51
Comments
-
You likely damaged the crossover(s) and/or drivers 5 years ago.Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
You likely damaged the crossover(s) and/or drivers 5 years ago.
Understandable. So short of pulling the cabinet completely apart and testing everything, I'm about out of luck yeah?Components in The Rack:
Yamaha RX-V765 7.1 AVR
Sony TA-N511 (from 1065 to sub)
Xbox One
MA PD-915R Power Strip
Monster HTS-1650
Speakers:
L/R- Polk TSI-500 Cherry, 12awg in place of jumpers
C- Polk CS20 Cherry
SRs- Polk TSI-100 Cherry
Sub- Kicker S12L5, vented box
Display:
Sony VPH-1252Q
75" 16:9 DIY BO Cloth Screen
Not running:
Crown Straight Line Two
Crown Power Line Four
Pioneer PD-F908
Fender BXR Dual Bass 400
Pioneer BDP-51 -
Your testing shows there is a problem, so now it's time to start looking for the cause.Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk
